1. Field of the Invention
This invention relates to an optical device capable of changing relative positions of two or more optical surfaces
2. Description of the Prior Art
Such an optical device, of which two optical surfaces are able to change their relative positions, as variable apex angle prism, variable thickness parallel flat plate, etc is useful for focusing or formation of anti-vibration optical systems. The devices of the prior art known as devices of this kind include a device in which a liquid is sealed between two parallel flat plate glasses, a device in which a liquid is sealed within a rubber film, sandwiched between two parallel flat plate glasses and deformed under pressurization, etc However, any of these devices employs a liquid, for which a liquid reservoir or a pressurizing device are required, thus posing many problems in miniaturization or production thereof.
It is also known to use a piezoelectric element as a deformation means, but such a device has the drawback that it can cause only a small amount of deformation.